It is common mistake to underestimate the anchor loads developed by an inline bellows joint. This is the case for both internally pressurized and externally pressurized joints. For inline bellows joint, the anchor load can be calculated by adding the three major loads together.
Pressure Thrust Pressure X effective area (Use the highest pressure possible, often the test pressure). The effective area of a bellows is often overlooked. The effective area can be found by calculating the area of the “mean” diameter of the bellows.
Deflection Load Published Spring Rate X movement of the joint. The deflection load is the force it takes to bend the stainless steel bellows
Frictional Resistance Total weight of pipe, media, insulation X .3 coefficient. The frictional resistance is the force it takes to overcome the friction of any hangers and guides in the piping system
For the effective area and spring rates vary from joint to joint. You can find the data of each joint with the bellow links.